History

Most patients with myxedema coma have a history of hypothyroidism. Some patients may have developed hypothyroidism after thyroidectomy or iodine therapy for hyperthyroidism. However, some patients will have undiagnosed hypothyroidism and myxedema coma will be the initial presentation.

Symptoms of hypothyroidism, including fatigue, weight gain, cold intolerance, constipation, and dry skin, may be elicited.

Patients have depressed mental state with lethargy, delirium, or coma.

Symptoms of the precipitating illness can be seen such as infection (commonly pneumonia), stroke, myocardial infarction, trauma, or heart failure.

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Causes

Myxedema coma is a physiologic decompensation of untreated hypothyroidism that is usually caused by a precipitating factor such as the following:

Infection

Exposure to cold temperatures

Trauma

Burns

Cerebrovascular accident

Myocardial infarction

Congestive heart failure

Respiratory acidosis

Medications such as the following:

Tranquilizers

Sedatives

Anesthetics

Narcotics

Amiodarone

Rifampin

Beta blockers

Lithium

Phenytoin

Gastrointestinal hemorrhage

Metabolic disturbances such as hypoglycemia, hyponatremia, acidosis, and hypercapnia

Ingestion of raw bok choy

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Physical Examination

Physical findings may include the following:

Hypothermia, which may not be recognized initially because many automatic thermometers do not register low body temperatures (It may be necessary to use special thermometers.)